Light-projecting reflector



Aug. 16, 1927. ,639 363 J. G. BALSILLIE LIGHT PROJECTING REFLECTOR Filed June 6, 1924 2 Sheets-Sheet 1 A 0mm Aug. 16 1927.

J. G. BALSILLIE LIGHT PROJECTING REFLECTOR Filed June 6, 1924 2 Sheets-Sheet 2 (avg-M OR A NW Patented Aug. 16, 1927.

JOHN GRAEME BALSILLIE, OF

MELBOURNE, VICTORIA, AUSTRALIA, ASSIGNOR, BY

MESNE ASSIGNMENTS, 'IO THE'AMERICAN FLATLITE COMPANY, OF CINCINNATI,

01110, A conronarrro'u or 01110.

LIGHT-PROJECTING REFLECTOR.

Application flled lune 6,

This invention relates to a light projecting reflector for vehicle head lamps, which has been developed, with an object in view of producing a construction designed to project a beam of light complying in a general sense with the requirements of the varying laws of the several States having regulations designed to govern vehicle road lighting, and

. which, in addition to meeting these requirements 'in a novel manner, simultaneously lends itself to very simple and relatively inexpensive manufacturing conditions and methods.-

These and other objects are attained in the. reflector described in the following specification and illustrated inthe accompanying drawings in which:

Fig. I is a front elevation of a reflector embodying my invention. Figf2 is a somewhat diagrammatic view showing the shape of light pattern produced by the reflector shown in Fig. 1.

Fig; 3 is a vertical sectional view of the reflector shown in Fig. 1 and taken on the line 3-3 thereof.

. Fig. 4 is a horizontal sectional view of the reflector shown in Fig. 1 and taken on the line 44 thereof.

Fig. 5 is a fragmental sectional view taken on the line 5--5 of Fig. .3.

The reflector which-I haveillustrated as an embodiment of my invention, has been shaped somewhat upon a curvature basis which is preferably that a hyperbola or which may be a parabola, an ellipse or a combination of these curves.

an aperture 5 adapted to receive the usual focusing tube and electric lamp bulb which furnishes the source of light. The forward openend of the reflector is provided with a I The rear or apex end of the reflector is provided with 1924. senaino. 718,288.

median as indicated by the line 414 of Fig 1. The embodiment I have disclosed is such that the sectors above the horizontal median are identical with those below the horizontal median and the sectors 8 and 9 which lie on each side of the reflector are separated by the horizontal line 44 so that half of each of these sectors lie on each side of the horizontal median. These sectors are preferably of the largest dimensions and the next largest in width are those which extend vertically and are designated by numerals 10 and 11. These vertical sectors are split by the vertical median as represented by line 33 in Fig. 1, so that one-half of each sector lies on each side of the median. Between each of the horizontal sectors 8 and 9 and the vertical sectors 10 and 11 I have divided the reflector surface into a series of sectors of smaller angular breadth and decreasing in width from the vertical sectors toward the ad acent edges of the horizontal sectors. The sectors 12, 13, 14, 15, 16, 17 and 18 which lie on each side of the vertical sector 10, are I preferably of the same angular breadth as are the corresponding sectors 12', 13', 14., 15, 16', 17', and 18', which lie on each side of the lower vertical sector 11. The horizontal sectors 8 and 9 are divided into a series of vertical stripes 19, 20, 21, 22, 23, 24, 25 and 26 which are preferably of uniform width, although, if desired they may be of varying width as are the sectors, depending upon the results desired. v

In as much as the example of light pattern to be produced has been shown as of the shape disclosed in Fig. 2, it is necessary that the various sectors and stripes be of the transverse cross sectional and other shape shown and the various features of which will be described shortly. However, 1

theshape of each ofthesectors and stripes may be materially varied in order to produce a light pattern which complies fully which is intersected by a portion 28 which'is of an elongated elliptical shape and which projects beyond the center portion 27 at each side. The-production of this composite pattern is brought about by the superposition and angular crossing of a number of subbeams which I have indicated by dotted outlines 29iand 30, each of these sub-beams is produced by one of the sectors and its corresponding sector located on diametrically opposite sides, or by one of the stripes and its corresponding stripe located on the opposite side of the reflector. The somewhat elliptical center section 27 of the light pattern, shown in Fig- 2, is made up of the sub-beams which are projected from the sectors 10, 11, 12, to 18 and 12 to 18 inclusive. The elongated elliptical portion 28 of the pattern disclosed in Fig. 2 is composed of projected by the sub-beams projected from the stripes 19 to 26 inclusive located on opposite sides of the reflector apex. Thus the composite beam produced by the series of superposed and angularly disposed sub-beams, will assume the general shape suggested by the total pattern disclosed in Fig. 2.

The practical desirability of such a pattern is readily seen in the three-fold function performed by its peculiar shape. In the first place the somewhat elliptical centrally located portion 27 operates to illuminate the roadway directly in front of the vehicle and for a considerable distance ahead of the vehiclewith a ribbon of light having a relatively narrow spread, thus forming nation to disclose ditches, embankments and objects located at the side ,of the road and for this reason the elongated elliptical portion 28 has been provided to furnish the necessary roadside illumination. Such a relatively narrow but wide beam of light will not afford illumination of the road surface at a great distance ahead of the vehicle but will function to illuminate the entire. road surface immediately in front of the vehicle so that both sides of the road are disclosed. Because-of thevnarrow characteristics of this portion of the totalbeam vreflector, the lightrays are held comparatively close to the ground and will not operate to create glare in the, eyes of the driver of an approaching vehicle;

Another advantage attained by t is combination of elliptical beams is that when the vehicle passes to the side of the road so that it tips after having left the crown of the road, the central portion 27 will still function to disclose distant objects while the narrow side projection of portion 28 will be too. narrow to project a glaring light into the eyes of the driver of an approaching vehicle,

even though this portion of the beam be somewhat elevated.

Change of general contour of the exemplary light pattern disclosed in Fig. 2. may be desirable and may be easily accomplished in order to bring the pattern within the requirements of the laws designed to regulate such matters. In the development of the reflector I have disclosed herein I have cliccovered a few general principles upon which the projection of the required pattern depends. I will endeavor to set forth in a few brief statements the general principles governing the variation of the shape of the pattern to be produced by the reflector enibodying my invention. In order that the somewhat elliptical portion of the beam disclosed in Fig. 2 may be produced, I have discovered that the sectors lying between the horizontally positioned sectors 8 and 9, must be of varying width, the width of the sectors decreasing from the vertically positioned sectors toward the adjacent edges of the horizontally positioned sectors. The ellipticity and distribution of the center portion of the light pattern depends upon angular position, angular breadth and transverse sectional curvature of sectors and the amount of ellipticity and distribution can be controlled by varying one or more of these factors. The elongated elliptical portion of the light pattern is projected by the vertical stripes in sectors 8 and 9. The transverse cross section of each of these stripes is different from that of the corresponding portion of the general or basic curvature upon which the reflector is designed. The stripe cross section may vary therefrom so as to be somewhat convex, and should greater ellipticity be required it is necessary to increase thisconvexity.

I have also discoveredthat when the sectors 10 to 18 and 11 to 18 lying between the horizontal sectors 8 and 9 are made of uniform width and are less convex in transverse cross section the central, portion 27 of thelight pattern will be substantially circular. Upon these principles and upon their variation in combination and degree, depends the production of any light pattern which may be required to meet the require ments of the several States providing laws for the regulation of vehicle high-way illumination.

Thus it will be seen that the latitude in the variation of the. widths, cross sectional shapes and in the number of sectors and stripes, may be varied infinitely in order to produce the required results, the permissible variation in the position of the stripes, as to angularity, etc., also operating as governin influences inthe production of the required light pattern.

I am aware that reflectors have been constructed heretofore upon lines resembling quite closely the radiating sector-like portions of the reflecting surface of my improved reflector, and that reflectors have heretofore been constructed with a reflecting surface made up-in its entirety of stripes or portions of stripes extending substantially vertically of the reflector, but I am not aware of any construction which discloses a reflecting surface of a composite nature in which portions thereof are made up of radiating sector-shaped sections, with other portions consisting of a number of substantially vertically extending stripes. Particularly do I consider the formation of the reflecting surface to be a novel one in the making of the entire surface into sectorshapes with certain of the sectors divided into stripes of decreasing lengths from the rim of the apex.

In reflectors of the substantially vertical stripe type the stripes decrease in' length from the center of the reflector toward each side thereof until the opposite longitudinal edges are reached. This type of reflector produces a truly elliptical beam without the centrally located distance piercing portion of the somewhat elliptical shape. In the reflector I have disclosed herein the reverse condition of the stripes is true. The decrease in length of these stripes takes place from the opposite horizontal edges toward the center, thus leaving the remaining portions of the reflector free for the formation of the sector shaped circular beam producing sections thereon, the striped sections thus being properly pro ortioned to reduce the side extensions 0 the elliptical part of the light pattern.

A reflector of concave formation, consisting of a' series of sectors, certain of said sectors consisting of a series of vertical stripes having contiguous edges of substantially parallel disposition relatively to each other, the striped sectors being arranged horizontally opposite each other with each containing substantially the same number of stripes as the other striped sector, the remaining of said sectors being arranged in two vertically opposite groups, each of which contains substantially the same number of sectors, each of the vertically opposite groups of sectors consisting of a relatively wide angular sector located at the center of each of the vertically opposite groups of sectors, and a series of sectors of decreasing angular width located upon each side of each relatively wide centrally located angular sector of the vertically disposed groups of sectors, with the narrowest one of the sectors of decreasing angular width on that side of the adjacent relatively wider angular sector which lies toward the series of horizontally opposite vertically striped sectors, the transverse cross section of each of the vertically disposed stripes of the horizontally disposed sectors and the "transverse cross section of each of the sectors of the second mentioned vertically opposite groups of sectors varying from the general concave formation of the entire reflector, whereby a sourceof light placed at or about the focal center ofthe reflector will produce a projected beam of desired contour and light intensity distribution conforming generally to a horizontally elongated ellipse.

In testimony whereof I have hereunto aflixed my signature.

JOHN GRAEME BALSILLIE. 

